Single wafer processor apparatus

ABSTRACT

A single wafer processing apparatus includes a portable processing head that can be a portable module or a movable unit mounted to a supporting machine frame. The processing head has movable fingers adapted to grip a wafer. The fingers protrude from a protective wafer plate. Indexing and rotation monitoring assemblies are provided for automation of the wafer processing steps. A complementary processing base includes an upwardly-open bowl that receives a wafer held by the portable processing head. It has a full-diameter movable bottom wall for rapid draining purposes. Liquid and/or gas jets and nozzles supply fluids required within the bowl for processing of wafers.

CROSS-REFERENCES TO RELATED CASES

This is a continuation of U.S. patent application Ser. No. 08/027,863,filed Mar. 8, 1993; now U.S. Pat. No. 5,445,172 which was a continuationof U.S. patent application Ser. No. 07/640,204, filed Jan. 11, 1991 (nowU.S. Pat. No. 5,222,310); which in turn was a continuation of U.S.patent application Ser. No. 07/526,243, filed May 18, 1990 (now U.S.Pat. No. 5,168,887).

TECHNICAL FIELD

This disclosure relates to single wafer processors for holding,transporting and processing individual semiconductor wafers inconjunction with fluid treatment of at least one wafer surface.

BACKGROUND OF THE INVENTION

Chemical processing of semiconductor wafers and similar substrates isoften carried out with respect to relatively large batches of wafers.Typically as many as twenty or thirty wafers are simultaneously immersedin a fluid (liquid or gas) or are subjected to fluid sprays. While thisis highly effective for rinsing and drying of wafers, as well as formany conventional high volume manufacturing applications, it is ofquestionable economy where more expensive wafers or substrates are beingprocessed, particularly during more complex or critical processingconditions. Such large-scale batch treatments of wafers multiplypotential loss due to malfunction in the processing steps. Batchhandling of wafers also interrupts the normal individualized handlingand development of more expensive and exotic wafers or substrates.

Individual handling and processing of wafers has also been increasinglydictated by the greater size of wafers coming into use today, ascompared to earlier wafers. Where wafers once were two or three inchesin diameter, some are now as large as eight inches in diameter, andwafers having a diameter of twelve inches are being used experimentally.This increase in size drastically increases the number of devices oneach wafer, and correspondingly increases their potential value.Manufacturers can no longer economically risk the loss of such largenumbers of devices to the many unpredictable variations encountered inbatch processing operations.

The present invention was developed to minimize such economic losses byhandling only a single wafer. It also adapts readily to existing singlewafer production techniques common in the semiconductor industry.Furthermore, in contrast with the treatment of large batches of parallelwafers arranged in a stack, the single wafer process as described hereinpermits treatment of one wafer surface (by application of liquid sprays)as well as both wafer surfaces (by immersion treatment). It also readilyaccommodates robotic transfer of each wafer between processing units andother automated handling equipment. Indexing and rotation of each wafercan be controlled to meet precise processing requirements.

The use of individual bowls in which process steps for single wafers areconducted also allows the user to minimize the amount of fluid requiredfor wafer processing. The smaller fluid volume requirements permit useof fresh fluid with respect to each wafer, thereby minimizing the amountof contamination that might otherwise be encountered when recirculatingfluids in larger volume systems.

The present invention pertains to components of a single waferprocessing station that includes a processing base and a complementaryprocessing head. The processing head can be portable for movement fromone location to another with no restrictions on its orientation orlocation, or can be movably mounted relative to a common framesupporting the processing base. The details of the processing head andprocessing base are subject to a number of variations, depending uponthe specific wafer processes to which they are directed.

BRIEF DESCRIPTION OF THE DRAWINGS

The preferred embodiment of the invention is illustrated in theaccompanying drawings, in which:

FIG. 1 is a central cross-sectional view through the apparatus;

FIG. 2 is a top plan view of the wafer support;

FIG. 3 is a side elevational view;

FIG. 4 is a bottom plan view;

FIG. 5 is an enlarged sectional view taken along line 5--5 in FIG. 1;

FIG. 6 is an enlarged sectional view taken along line 6--6 in FIG. 1;

FIG. 7 is a side elevational view of the indexing and motion monitoringassemblies as seen along line 7--7 in FIG. 1;

FIG. 8 is an enlarged fragmentary sectional view taken along line 8--8in FIG. 4;

FIG. 9 is a top view of a four station processing machine;

FIG. 10 is a front view;

FIG. 11 is an end view;

FIG. 12 is a side elevation view of the processing station components ina closed position;

FIG. 13 is an enlarged partial sectional view of the processing headsupport;

FIG. 14 is similar to FIG. 12, showing the processing station in an opencondition;

FIG. 15 is a fragmentary side elevation view of the processing stationshowing the open processing head pivoted to a vertical position; and

FIG. 16 is a view similar to FIG. 12, showing addition of a rotaryactuator for the processing head.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following disclosure of the invention is submitted in furtherancewith the constitutional purpose of the Patent Laws "to promote theprogress of science and useful arts" (Article 1, Section 8).

A single wafer processing apparatus constructed according to thisinvention might include a processing head that is constructed as a fullyportable unit (FIGS. 1-8) for engagement by a conventional robotic armor as a movable module (FIGS. 9-16) mounted on a machine base.

When used as an attachment to a robotic arm, the processing head can bemoved to or from a wafer receiving and discharging station. There waferscan be automatically or manually placed or removed between movablefingers carried by the processing head. The processing head can also bemoved to one or more receiving bases mounted in horizontal or uprightorientation in a processing cabinet housing chemical cells and suppliesof liquids and gases required during a specified process for the wafer.

When movably mounted on a machine frame, the processing head can berobotically loaded or unloaded in a first open position relative to theframe and can be shifted to a processing position or positions relativeto one or more complementary processing bases on the frame.

The above equipment is described only for the purpose of illustratingthe general environment within which this wafer processing apparatusmight be utilized. Further details of the supporting robotic and processequipment are not believed necessary for an understanding of the presentinvention, which relates to the structure and operation of theprocessing head and complementary processing base.

The processing head, shown designated generally at 12 in the drawings,is designed for handling a single semiconductor wafer 10 (FIG. 1) havingat least one surface to be subjected to contact with a processing fluid.The processing head 12 can transport an engaged wafer 10 to and from aprocessing base 70, either as a free-standing portable module or as acaptive movable unit on a common machine frame. In both instances, theprocessing head has the capability of selectively rotating an engagedwafer 10 while the wafer is suspended below it within a processing fluidor while one or both wafer surfaces are subjected to a fluid spray orstream.

The processing head 12 is centered about a first reference axis, shownin FIG. 1 as axis X--X. Mounting means is provided on the processinghead for attaching it to a movable support. The processing head 12detailed in FIGS. 1-8 has a mount 14 adapted to be attached to a roboticsupport (not shown), such as an articulated arm capable of moving theprocessing head 12 to a variety of positions and orientations duringhandling of a wafer. The mount 14 is of conventional designcomplementary to the robotic equipment with which it is to be used. Itsdetails are unnecessary to an understanding of the present improvements.

Processing head 12 includes a removable cover 13, a structural motorbase 15 and rigid supporting spacers 16 that fix mount 14 to motor base15. Processing head 12 also includes a radially enlarged circular shroud18 that is outwardly open along axis X--X. The dished shroud 18 is fixedacross one axial end of the processing head 12. Shroud has a peripheralrim centered about the reference axis X--X adapted to elevationallysupport the processing head 12 with its one axial end facing downwardly;

A solid wafer plate 30 is coaxially centered about the axis X--X at theone axial end of the processing head 12. Wafer plate 30 is a rigidcircular disk having opposed inner and outer surfaces 31, 32 and aninwardly projecting peripheral flange 33. The-outer peripheral cornerformed about the circular wafer plate 30 is relatively sharp andwell-defined to facilitate the radial exit of fluid along its outersurface 32.

Flange 33 overlaps a complementary cylindrical flange 20 about theinterior of shroud 18, and closely abuts a peripheral horizontal flange19 about the rim of shroud 18. The flanges 19, 20 and 33 form a baffleto prevent entry of liquid into the open chamber between thenonrotatable shroud 18 and the rotatable wafer plate 30. The horizontalflange 19 further serves as a support for processing head 12 whileresting on a processing base 70 in an inverted position, as shown inFIG. 1.

The periphery of shroud 18 also mounts a radially projecting electricalcoupler 22 adapted to be connected to an electrical receiver 23 on acomplementary processing base 70. Electrical power and control circuitsfor the equipment within the processing head 12 are completed by thisconnection. The electrical coupler and receiver 22, 23 are ofconventional design. Their details are unnecessary to an understandingof the present improvements.

Drive means are provided in the processing head. The drive means isoperably connected to the gripper means for selectively rotating thegripper means relative to the processing head 12 and shroud 18 about thereference axis X--X.

The wafer plate 30 is selectively rotated by a motor 34 located withincover 13. Motor 34 rotatably powers a driven shaft 35 having anenlargement 36 fastened to the inner surface 31 of wafer plate 30. Thedriven shaft 35 in turn is powered by a surrounding tubular motor driveshaft 38. Driven shaft 35 and drive shaft 38 are coaxially centeredabout the reference axis X--X of processing head 12.

The drive shaft 38 and driven shaft 35 are axially splined to oneanother. They are held in an assembled condition by an enlarged nut 39that threadably engages driven shaft 35 and radially overlaps the innerend of drive shaft 38.

The above-described shaft assembly permits easy substitution of waferplates 30 as required to support wafers 10 of different configurationsor sizes. Substitution or repair of a wafer plate 30 can be readilyaccomplished by removal of nut 39 at the outer end of the portableprocessing head. One can then move the driven shaft 35 and wafer plate30 axially from the remainder of the processing head 12. No interioraccess is required in the vicinity of wafer plate 30 to accomplish itsassembly or disassembly.

Gripper means is provided on the processing head 12 for holding a wafer10 in a coaxial position perpendicular to the reference axis X--X, thegripper means being axially and radially overlapped by shroud 18. Thegripper means includes a plurality of movable gripping fingers. 40 whichselectively hold a wafer 10 at a location adjacent to the outer surface32 of wafer plate 30. The fingers 40 protrude axially to both sides ofthe wafer plate 30. Each is notched at 41 adjacent to its outer end toreceive and engage the edges of a wafer 10.

Fingers 40 are geometrically arranged about the reference axis ofprocessing head 12 to receive and grip a wafer 10 within notches 41 in acoaxial position perpendicular to the axis X--X. Three fingers 40 areshown in the illustrated apparatus, but four or more fingers can be usedwhen desired.

As shown in FIG. 8, each finger 40 is individually mounted in the waferplate 30 within a flexible supporting diaphragm 42. The periphery ofeach diaphragm 42 presents a seal 43 engageable within the periphery ofa complementary aperture formed through the wafer plate 30. The innerperiphery of the seal is releasably held in place by a snap ring 44.Each diaphragm 42 is molded or otherwise formed integrally with onefinger 40. This integral connection and support for the individualfingers 40 eliminates seams or openings across the wafer plate 30, whilepermitting the limited movement of finger 40 required to engage ordisengage a wafer 10. Only the operative wafer-engaging section of eachfinger 40 is exposed to the processing fluids and gases outwardly of thewafer plate 30.

Finger control means are located inwardly of the wafer plate 30 in theprocessing head 12 for moving fingers 40 in unison between closedpositions engaging a wafer between them and open positions to permitreceipt or discharge of a wafer. The finger control means comprises acombination of individual lever assemblies mounted about the innersurface 31 of wafer plate 30 and a common actuator assembly mountedwithin the motor base 15.

The common actuator assembly is operably engageable with the individuallever assemblies for selectively moving the fingers in unison from theirclosed positions to their open positions. The actuator assembly does notphysically engage the individual lever assemblies during normaloperation and rotation of the wafer plate 30 in conjunction with theprocessing of a wafer 10.

The individual lever assemblies are connected respectively to theindividual fingers 40. They yieldably bias fingers 40 to their closedpositions and selectively move the fingers to their open positions. Eachof the individual lever assemblies for the fingers 40 includes a radiallinkage bar 45 spaced inwardly from wafer plate 30. The outer end ofeach linkage bar 45 is pivotally connected to the inner end of thefinger 40 controlled by it. Its inner end is pivotally connected to apivot arm 46 mounted to a parallel pivot shaft 47. A torsion spring 53wrapped about each pivot shaft 47 yieldably urges the associated pivotarm 46 to an upright or inwardly protruding position as illustrated inFIG. 1, where the fingers 40 are in a closed position parallel to thereference axis X--X.

An annular push ring 50 overlies the inner ends of the linkage bars 45adjacent to the motor base 15. Motor base 15 has two cylinders formeddiametrically apart through reference axis X--X. Each mounts an axiallymovable pneumatic piston 51 having a protruding piston shaft 52 fixed tothe push ring 50.

Pistons 51 are inwardly biased by surrounding compression springs 53.Piston springs 53 normally maintain push ring 50 clear of engagementwith the underlying linkage bars 45. When compressed air is directed tothe inner side of piston 51, the piston shaft 52 and push ring 50 extendaxially to depress the pivot arms 46 about pivot shaft 47 and therebypull the inner ends of fingers 40 radially inward to permit a wafer 10to be positioned for subsequent gripping by the fingers 40. The grippingmovement is effected by the yieldable spring forces on pivot arms 46when the pressure of push ring 50 is released by terminating applicationof pneumatic pressure to the piston 51.

It is important to provide control of the angular positions of fingers40 about reference axis X--X to accommodate the needs of automatedequipment for loading and unloading of wafers. Indexing means for thispurpose is provided within processing head 12. It selectively positionsthe fingers 40 in preselected angular locations about the reference axiswhen the wafer plate 30 is not being rotated by motor 34.

Indexing is accomplished by a multi-sided rotor plate 59 having aplurality of sides equal in number to the fingers 40 on a particularwafer plate 30 with which it is used. Each side of rotor plate 59 has acurved edge configuration (shown in FIG. 5) that serves as a detent incombination with an inwardly-biased roller 60. When the motor 34 isinoperative and drive shaft 38 is freely rotatable, the inward biasingforce of roller 60 will cause rotor plate 59 to pivot an angular amountnecessary to center roller 60 across the engaged side of rotor plate, 59in the centered position shown in FIG. 5.

Roller 60 is mounted at one end of a crank arm 62 pivotally supported ona supporting shaft 63 depending from the mount 14. The opposite end ofcrank arm 62 includes a clevis 64 pivotally joined to the outer ends oftwo parallel piston rods 65 that are part of two parallel pneumaticcylinder assemblies 66. The remaining ends of the cylinder assemblies 66are pivotally mounted about a parallel axis on a spacer 67 that joinsthe motor base 15 and mount 14.

The cylinder assemblies 66 are normally spring biased to a retractedposition where roller 60 is radially clear of the rotor plate 59, whichrotates in unison with the drive shaft 38. However, when rotation ofdrive shaft 38 terminates and indexing of the wafer plate 30 isrequired, the cylinder assemblies 66 are extended. This forces roller 60radially inward against the edge of rotor plate 59 and properly centersthe rotor plate as shown. The detent assures that the fingers 40 areangularly indexed when stationary to thereby meet operationalrequirements of associated robotic wafer handling equipment.

A motion monitoring assembly is also provided within processing head 12for measuring the speed and direction of rotation of the wafer plate 30about the reference axis X--X. This is illustrated by an optical disk 54fixed to the drive shaft 38 and provided with a plurality of smallnotches 55 and interspersed large notches 56. One or more optical sensor57 overlie disk 54 to read the two sets of notches. The positions of thelarge notches 56 are utilized to confirm the angular position of therotor plate 59 and held by the detent roller 60 in a stationaryposition. Additional sensors can be utilized to measure speed anddirection of the disk by monitoring movement of the small notches 55.The details of such optical monitoring are well known and not necessaryto an understanding of the present improvements.

The general details of the processing base 70 are shown in thecross-sectional presentation of FIG. 1. It basically comprises anupwardly open bowl formed by a combination of a stationarycircumferential upright wall surface 71 and an axially movable bottomwall 72. The bottom wall 72 is adapted to be shifted axially tosealingly engage the bottom edge of the upright wall 71. When lowered,the bottom wall 72 allows any liquid within the bowl to drain about itsfull periphery.

The upright wall surface 73 and outer surface of bottom wall 72 togetherform an upwardly-open bowl interior centered about a second referenceaxis. This second reference axis of the processing base 70 is alsoidentified in FIG. 1 by axis X--X, since the first and second referenceaxes of the portable processing head and supporting processing base 70are coaxial when used in conjunction with one another.

The inner diameter of the cylindrical surface 73 within the bowlrelative to the axis X--X is greater than the outside diameters of thefingers 40 relative to the axis. This provides clearance within theupwardly open bowl for reception of the gripping fingers 40 whichposition a wafer 10 within the bowl interior.

Mounting means is located about the bowl for selectively holding aprocessing head with the first and second reference axes in a fixedcoaxial relationship illustrated by axis X--X in FIG. 1 and with thefingers 40 gripping a wafer within the bowl interior. The mounting meanscomprises an upwardly-facing peripheral flange 75 extending radiallyoutward about the upright wall 71. The flange 75 is complementary to theflange 19 formed about shroud 18, which freely rests upon it to properlylocate the processing head 12 on the processing base 70.

An annular trough 78 is interposed between the upright wall surface 73and the supporting flange 75 about the processing base 70. Trough 78serves to collect liquid that escapes radially outward over the uprightwall surface 73 during rotation of the wafer plate 30 and associatedwafer 10. It also acts as an overflow for the upwardly open bowl orbasin when immersion processing techniques are being carried out withinit.

The components of the processing base 70 are located within a baseenclosure formed by a surrounding cylindrical wall 79 and lowerhorizontal wall 82. The walls 72, 82 can be apertured as required foraccess of hoses, drains, pipes and other supply fittings to the interiorof the enclosure. The base enclosure mounts the processing base 70within a surrounding frame support 88.

The bottom wall 72 of the processing bowl is supported by an annularbellows 80 extending about its full periphery to lower wall 82. Bellows80 is interposed between the lower wall 82 and the lower wall 72 of thebowl for movably supporting bottom wall 72 during axial movementrelative to the upright wall 71.

Linear actuators are provided in the processing base 70 to move thebottom wall 72 parallel to axis X--X between the closed position shownin FIG. 1 and a lowered open position. These linear actuators areillustrated by one pneumatic cylinder assembly 84 in FIG. 1. In actualpractice, a plurality of such cylinder assemblies 84 will be provided tomove the relatively large bottom wall 72 in the required axial path. Adrain 85 is provided in lower wall 82 at the exterior of bellows 80 forcarrying away liquid received from within the bowl and from within thepreviously-described trough 78.

Any suitable number of liquid or gaseous jets or nozzles can be directedinto the interior of the bowl. One illustrative jet 86 is shownextending through the movable bottom wall 72, although a plurality ofsimilar jets or nozzles can be provided in any desired geometric patternto direct fluid or gas against the facing surface of a wafer 10 in therequired pattern. Alternatively, nozzles extending through the bottomwall 72 can be used to fill the bowl during processing and to circulateprocessing fluid as required. Peripheral liquid or gas supply nozzlesand jets can also be provided about the cylindrical surface 73, asillustrated by the single jet 87 shown at the left side of FIG. 1.

The processing base 70 lends itself to a wide variety of semiconductorwafer processing techniques requiring spraying of liquids and/or gases,as well as immersion within liquids. The illustrated bowl assemblypermits rapid dumping of liquids from within the bowl interior. This isaccomplished by moving the bottom wall 72 downwardly, which allowsliquid to escape about its full periphery.

FIGS. 9-11 generally illustrate one self-contained machine applicationfor the processing station previously described. In this application,the processing head 12 and processing base 70 are essentially identicalto that detailed in FIG. 1. The processing base 70 is stationary andsupported by the frame support 88, shown as a horizontal upper cabinetsurface interrupted by one or more apertures 90. The open periphery ofeach aperture 90 is complementary in shape to the exterior of the baseenclosure and the adjacent linear actuating mechanism for the processinghead 12, which is described below. The interconnection between eachprocessing head 12 and its associated processing base 70 are illustratedin FIGS. 12-16.

The machine shown in FIGS. 9-11 is a processing machine forsemiconductor wafers. It includes four processing stations. In thedrawings, three of the processing stations are shown with the processingbase 70 and processing head 12 in closed positions on the upper surfaceof a machine cabinet. These components are not shown at the fourthprocessing station in order to illustrate the general shape of thereceiving aperture 90.

The machine cabinet also supports a pair of conventional portable wafercarriers 91 of a type conventionally used for supporting a stack ofparallel semiconductor wafers during handling and transport. Incomingwafers would be handled by one carrier and processed wafers by theother.

A universally movable and programmable robotic transfer arm assembly 92is located centrally on the machine frame 88 for transferring individualwafers between carriers 91 and the four processing stations. Theprocessing stations on a given cabinet might all be used for a commonprocessing method involving application of one or more fluids to thesurface(s) of a wafer positioned within them by the processing heads 12,or might be used in a sequence of processing steps wherein wafers aretransferred from one processing head 12 to the next by operation of therobotic transfer arm 92.

In the embodiment of the processing head shown in FIGS. 12-16, theprocessing head 12 is cantilevered by a radial arm 93. The arm 93 ishorizontal and upwardly adjacent to the previously-described shroud 18.The outer end of arm 93 is pinned to a support bracket 95 that serves asthe previously-described mounting means provided on the processing headfor attaching it to a movable support. In this embodiment, the bracket95 is fixed to the upper end of a vertically movable support shaft 100.

Shaft 100 is hollow and cylindrical. It is slidably surrounded by asupporting tube 94 fixed to the lower wall 82 of the associated baseenclosure by a bracket 110. A guide bearing 111 on the base enclosurealso surrounds and slidably receives shaft 100 to stabilize its axialmovement relative to tube 94.

The upper and lower ends of tube 94 are slidably sealed about theexterior of support shaft 100. An intermediate piston 96 is fixed to theexterior of support shaft 100 within tube 94 and sealingly engages theinside walls of tube 94. This forms a double acting pneumatic cylinderin which shaft 100 is the axially movable member. The support shaft 100can be urged upwardly by introduction of pressurized air through thelower end of tube 94. It can be urged downwardly by introduction ofpressurized air through the upper end of tube 94.

In the form of the processing station shown in FIGS. 12-15, rotation ofshaft 100 relative to tube 94 about their coaxial vertical center axisis prevented by a guide rod 97 that depends downwardly from the lowerend of tube 94. The guide rod 97 slidably fits within an apertured guidecollar 98 fixed to the lower end of support shaft 100. The interactionbetween guide rod 97 and collar 98 assures proper angular positioning ofthe processing head 12 about the vertical axis of support shaft 100 toassure proper mating between the processing head 12 and the associatedprocessing base 70.

In addition to the limited vertical movement that can be imparted toprocessing head 12 by operation of the pneumatic cylinder assembly,processing head 12 can be pivoted about a vertically movable horizontalaxis to the position shown in FIG. 15. This is accomplished manually byfirst removing an inner pin 101 interconnecting the outer end of radialsupport arm 93 and the support bracket 95. Removal of pin 101 frees theprocessing head 12 for pivotal movement about the horizontal center axisof the remaining pin 102. The processing head 12 might be raised to theposition shown in FIG. 15 to permit substitution or repair of the waferplate 30 and associated equipment, as described above.

Removal of the second pin 102 permits replacement of the entireprocessing head 12 on the upper end of shaft 100 when such substitutionis desired. The electrical connections required between the reciprocableprocessing head 12 and the interior of the machine frame 88 can be madeby flexible cables extending through the hollow support shaft 100 to adetachable electrical coupling 104 housed within a removable cover 103that forms part of the radial support arm 93.

The processing heads 12 illustrated in FIGS. 9-15 are capable of limitedvertical movement relative to the machine frame 88. They pop up and downin response to pneumatic pressure applied to their respective supportingpneumatic cylinder assemblies. When in their raised positions, theexposed fingers 40 can be spread apart to facilitate transfer of a waferby operation of the robotic transfer arm 92. When lowered, the fingers40 engage and locate a wafer 10 within the upwardly open processing bowlfor exposure to processing fluids.

In some instances it might be desired to also impart rotational movementto the processing head 12 relative to the vertical center axis of shaft100. As an example, such rotary action might shift the raised processinghead 12 between two or more processing bases 70 positioned angularlyabout the vertical axis of support shaft 100 to sequence the wafergripped by the processing head 12 through two or more processing steps.

Such pivotal movement can be accomplished as illustrated in FIG. 15,where a rotary actuator 106 has been substituted for the vertical guiderod 97 and guide collar 98 shown in the preceding embodiment. Rotaryactuator 106 can be a hydraulic motor or electric motor designed to turnprocessing head 12 about the axis of shaft 100 any desired angulardistance.

The rotary actuator 106 can be selectively operated to pivot the lowerend of shaft 100 about its central vertical axis through interconnectingsplines 105. The splines 105 can also accommodate vertical movement ofshaft 100 and processing head 12 in response to actuation of thepneumatic cylinder assembly described above and illustrated in FIG. 13.

The apparatus described in FIGS. 9-16 maintains each wafer 10elevationally beneath the processing head 12, where it the wafer isprotected from contamination by contact of falling particulates. Thecomplementary processing heads 12 and processing bases 70 formenclosures that minimize contamination within the space where processingof each wafer takes place. When desired, this space can be pressurizedby introduction of compressed neutral gases to assure that contaminantscannot enter the enclosure formed by the processing head 12 and base 70.

The above-described processing stations are extremely versatile. Theyadapt to installations where it is desired that wafers are moved to andfrom a head movably supported on a processing cabinet or frame, as wellas to installations where the head is required to be moved betweenmultiple wafer handling and processing stations. In each type ofinstallation, the wafers are securely and accurately gripped by thesupporting fingers 40, and the adjacent shroud 18 is available to coverthe wafer and minimize contamination of its surfaces during movement ofthe processing head 12.

In compliance with the statute, the invention has been described inlanguage more or less specific as to structural features. It is to beunderstood, however, that the invention is not limited to the specificfeatures shown, since the means and construction herein disclosedcomprise a preferred form of putting the invention into effect. Theinvention is, therefore, claimed in any of its forms or modificationswithin the proper scope of the appended claims appropriately interpretedin accordance with the doctrine of equivalents.

We claim:
 1. A wafer processing apparatus, comprising:a frame; aplurality of processing bases supported upon the frame; a plurality ofprocessing heads, each of said processing heads being capable of acomplementary relationship with at least one processing base to form aprocessing station with an enclosure in which wafers are processed; saidprocessing heads and processing bases being mounted to allow relativemovement between the processing heads with respect to a complementaryprocessing base between an open position and a closed position; and atleast one wafer transfer means supported upon the frame for movingwafers between at least two processing stations.
 2. The wafer processingapparatus of claim 1:wherein the plurality of processing headsinclude:gripper means for selectively engaging the edges of a wafer; andwherein the plurality of processing bases include:an upwardly open bowl;and further comprising movable support means operably connected betweenthe processing head and the frame for selectively moving the processinghead relative to the processing base between an open transfer positionwhere the processing head is clear of the processing base and a closedprocessing position wherein the processing head encloses the processingbase and a wafer engaged by the gripper means is positioned within thebowl of the processing base.
 3. The wafer processing apparatus of claim1, wherein the processing heads have means for holding wafers on theprocessing heads.
 4. The wafer processing apparatus of claim 1, whereinthe processing heads have means for holding wafers on the processingheads which include gripper means which selectively engage edges of awafer being held therein.
 5. The wafer processing apparatus of claim 1,wherein the plurality of processing heads have drive means for rotatingwafers supported upon the processing heads.
 6. The wafer processingapparatus of claim 1, wherein the plurality of processing bases includean upwardly open bowl.
 7. The wafer processing apparatus of claim 1,wherein the plurality of processing bases include at least one supplyfitting for supplying a processing fluid thereto.
 8. The waferprocessing apparatus of claim 1, wherein the plurality of processingbases includes at least one supply fitting for supplying a processingfluid thereto.
 9. The wafer processing apparatus of claim 1, furthercomprising movable support means operably connected between theplurality of processing head and the frame for selectively moving theprocessing head relative to the processing base between an open transferposition where the processing head is clear of the processing base and aclosed processing position wherein the processing head encloses theprocessing base and a wafer engaged by the gripper means is positionedwithin the bowl of the processing base.
 10. The wafer processingapparatus of claim 9, wherein the movable support means interconnectsthe processing head to the frame for axial motion in a directionperpendicular to the plane of a wafer engaged by the gripper means. 11.The wafer processing apparatus of claim 9, wherein the movable supportmeans interconnects the processing head to the frame for pivotal motionabout a fixed vertical axis on the frame.
 12. The wafer processingapparatus of claim 9, wherein the movable support means interconnectsthe processing head to the frame for pivotal motion about a movablehorizontal axis on the frame.
 13. The wafer processing apparatus ofclaim 9, wherein the movable support means comprises:a shaft centeredabout a vertical axis on the frame; linear actuator means operablyconnected between the frame and the shaft for selectively reciprocatingthe shaft relative to the frame along the vertical axis; and bracketmeans operably mounting the processing head to the upper end of theshaft.
 14. The wafer processing apparatus of claim 9 wherein the bracketmeans includes a horizontal pivot connection between the processing headand the shaft.
 15. The wafer processing apparatus of claim 9, whereinthe movable support means comprises:a shaft centered about a verticalaxis on the frame; linear actuator means operably connected between theframe and the shaft for selectively reciprocating the shaft relative tothe frame along the vertical axis; and rotary actuator means operablyconnected between the frame and shaft for selectively pivoting the shaftrelative to the frame about the vertical axis, bracket means operablymounting the processing head to the upper end of the shaft.
 16. Thewafer processing apparatus of claim 1, further comprising movablesupport means operably connected between the plurality of processingheads and the frame for selectively moving the processing heads relativeto the processing base between an open position and a closed position.